The Income Tax department, probing the secret list of account holders in the Geneva branch of HSBC bank, has approached Swiss revenue authorities for banking data of certain individuals after investigations showed some of them reportedly had other accounts under fictitious names.

The department, which approached the Finance Ministry and the Central Board of Direct Taxes (CBDT) in this regard recently, has initiated the step in order to build a water tight case against those who have stashed illegal funds abroad and the action has been taken under the recently revised tax information exchange treaty between the two countries.

Top sources involved in the probe said that after India received the list, both the I-T department and the Enforcement Directorate (ED) have gathered vital leads on the financial investments of a certain number of individuals and it is suspected that a number of them hold other Swiss accounts under different names allegedly to evade the tax scanner.

The department, sources said, has also opened I-T assessments of a "specific number" of those named on the same list under the provisions of Wealth Tax laws.

The department, through the foreign taxation wing of the CBDT, has approached Swiss authorities as India can now "get information even if it only has limited details regarding the person having bank accounts in Switzerland".

This was not possible prior to May this year.

These "limited details" related to other Swiss bank accounts, sources said, were obtained by tax sleuths after investigations were conducted in various cities, acting on the HSBC Geneva list entities which was provided by the French government last year.